1. Field of the Invention
The present invention relates to a system of electronic reprographics and, more particularly, to a system of electronic reprographics in which scanned images are deleted from memory upon detection of a scanner fault.
2. Description of the Related Art
In light lens printing systems, a lamp or flashing unit flashes light on a document and has an image created synchronously on a photoreceptor belt. The photoreceptor belt picks up toner from which a copy is made.
In electronic reprographic printing systems, a document or series of documents comprising at least one print job are successively scanned. Upon scanning of the documents, image signals are obtained and electronically stored. The signals are then read out successively and transferred to a printer for formation of the images on paper. Once a document is scanned, it can be printed any number of times or processed in any number of ways (e.g., words deleted or added, image magnified or reduced, etc.). If a plurality of documents comprise a job which is scanned, the processing or manipulation of the scanned documents can include deletion of one or more documents, reordering of the documents into a desired order, or addition of a previously or subsequently scanned document or documents.
For a variety of reasons, operation in an electronic reprographic system can be interrupted. This can be the result of a scanner or printer fault, hardware or software faults, paper misfeed, intentional interruption, memory loss, etc. Upon such an interruption due to scanner fault, the operator, not knowing precisely where the scanner ceased operation, must either scan the entire job over again, initiate scanning at a document believed to precede the last scanned document and remove duplicate sheets from the job, or proof what has been scanned so far. Because the image signals are electronically stored immediately after scanning, a scanner fault can result in incomplete, erroneous, blank, etc. images being retained in memory. When a crash occurs while the scanner is building a job, documents present in the paper path can be damaged and the integrity of the job cannot be guaranteed.
Copending U.S. patent application Ser. No. 07/589,541, now U.S. Pat. No. 5,148,286 discloses a method and apparatus for operating an electronic reprographic printing system upon detection of a fault. The application describes the recovery operation upon detection of a fault. The operator is advised of precisely where to re-initiate scanning upon detection of a scanner fault so that the integrity of the job is guaranteed. Instructions are further provided regarding clearance of the paper path in response to the interruption of scanner operation so as to prevent document damage.
Other related art discloses printing systems which perform job recovery upon detection of a scanner fault.
U.S. Pat. No. 4,130,354 to Steiner discloses a reproduction machine having duplex job recovery capabilities which adjusts a reproduction process in the event of a fault condition so that the required number of copies are ultimately produced even though some may have been lost due to the fault. Counters are used to track the two sides of the copies made in a job. If, at the end of a job, these counters are not equal to one another or to the amount of copies requested, the reproduction process is automatically adjusted to correctly produce the required copies.
U.S. Pat. No. 4,206,996 to Clark et al. discloses a job recovery method and apparatus. During a duplex production run, if a fault or jam is detected, recovery is effected by 1) removing the jam; 2) inserting blank sheets as the job is continued to flag the position of each jammed copy in the generated stack of paper; 3) rerunning the original through the copy device after completion of the initial run, only copying necessary copies needed to replace the jammed copies; and 4) inserting the new replaced copies in the initial run stack, thus replacing the blank inserted flag sheets to provide a complete job.
U.S. Pat. Nos. 4,229,100 to Travis and 4,163,897 to Hubbard et al. disclose an automatic copy recovery method which recovers from loss of copy sheets due to a jam or other stoppage. A first flag is set when images are to be copied to both sides of a copy sheet and a second flag is set after first side copies are made. A plurality of separate counts of copy sheets are made. From the counts and the flag settings, recovery can be provided with accurate billing.
U.S. Pat. No. 4,327,993 to Gauronski et al discloses a method and apparatus for performing job recovery in a reproduction machine which reprimes or adds to copy sheets already in a tray to make up for damaged or lost copies without having to reject a whole set of copies.
While the related art attempts to recover from scanner faults by replacing faulted documents, the art does not suggest any type of job recovery which can be used in an electronic printer which stores electronic images in memory. Such systems are unique in that once the documents are initially scanned, the document images are converted to electronic images for storage in memory. Sheet replacement is not sufficient to adequately recover from a detected scanner fault.